Coated articles are known in the art for use in window applications such as vehicle windshields, insulating glass (IG) window units, monolithic vehicle windows, and/or the like.
U-value (sometimes referred to as U-factor) is a measure of heat loss in a building element such as a wall, floor, window or roof. It can also be referred to as an overall heat transfer co-efficient and measures how well parts of a building transfer heat. This means that the higher the U-value the worse the thermal performance of the building envelope. A low U-value usually indicates high levels of insulation. In other words, U-value measures how well a product prevents heat from escaping a home or building. The lower the U-value, the better a product is at keeping heat inside the building. U-value herein is measured in units of BTU/hr-ft2-° F.), and is calculated according to NFRC 2010 (which includes NFRC 100-2010 Winter) at the center of the glazing (COG). U-value as used herein refers to winter/night U-value.
Solar Heat Gain Coefficient (SHGC) measures how much heat from the sun is blocked. SHGC is expressed as a number between 0 and 1. The lower the SHGC, the more a product is blocking solar heat gain. Blocking solar heat gain is particularly important during the summer cooling season in hot climates. However, people in colder climates may want solar heat gain during the cold winter months to lessen the cost of heating the home. SHGC herein is calculated according to NFRC 2010. SHGC values herein are measured in the out→in context of the IG window unit unless stated otherwise.
Coated articles may or may not be heat treated. The heat treatment (HT) of such coated articles typically requires the use of temperature(s) of at least 580 degrees C., more preferably of at least about 600 degrees C. and often at least 620 degrees C., for about 5-10 minutes or more, such as for thermal tempering or the like. The terms “heat treatment” and “heat treating” as used herein mean heating the article to a temperature sufficient to achieve thermal tempering, heat bending, and/or heat strengthening of the glass inclusive coated article. This definition includes, for example, heating a coated article in an oven or furnace at a temperature of least about 580 degrees C., more preferably at least about 600 degrees C., for a sufficient period to allow tempering, bending, and/or heat strengthening. In certain instances, the I-IT may be for at least about 4 or 5 minutes or more.